Electrical condenser



Oct. 25, 1938. y, BUSH: 2,134,273

ELECTRICAL CONDENSER Original Filed Oct. 1, 1926 I --L gins UNITED STATES PATENT OFFICE ELECTRICAL CONDENSER Vannevar Bush, West Medford, Mass., assignor, by

mesne assignments, to Raytheon Manufacturin; Company, Newton, Mass, a corporation of Delaware Application October 1, 1926, Serial No. 138,900

Renewed November 22, 1933 10 Claims.

The present invention relates to devices for the storing of electrical energy and in particular, to

a condenser formed by employing electrodes which are immersed in electrolyte and by passing an electriccurrent between the electrodes to produce a film thereon. This film subsequently acts as a dielectric of high constant, the stress of which caused by the applied potential enables the unit to retain energy in electrostatic In the particular embodiment illustrated in Figs. 1 and 2, numerals l and 2 designate two sheets of a metal, as aluminum, nickel or one of its alloys as nickel-silicon, which is strongly oxidized when subjected to an electrolyte. However, I prefer to use electrodes of nickel-silicon, the oxidation products of which are stable and of a strongly adhesive character. It will be noted that inasmuch as the electrodes are of like maform. terial, the condenser has no initial polarity. At 10 Now it has been found in condensers her to- 3, I have indicated a sheet of porous electrically fore known to the art that upon rupture or leakinsulating Subs as as blotting p per. age of easing enclosing the condenser proper, the or the like, the function of which is to space the film forming liquid evaporates rendering'th demetallic electrodes and to absorb electrolyte or vice 11581655 after a ort; period of t film forming liquid 4. For the latter, I prefer to 15 The primary object of my invention therefore is to provide condensers of the above type in which the dielectric forming liquid is hygroscopic whereby solidification is precluded. A further object resides in producing a structure which is substantially devoid of electrolytic action after the dielectric has been formed. Still another object is to devise structure which offers cheapness and simplicity of manufacture but nevertheless, is capable of retaining a large charge for a considerable period of time.

"inasmuch as the condenser described hereinutilize a hygroscopic or deliquescent liquid, for example potassium acetate (KC2H302), which, having afiinity for water, will absorb moisture from the atmosphere in the event of a punctured, broken or porous container. Due to its ability of extracting water, the acetate remains of the same constituency throughout its life, and accordingly, congealation and solidification are effectively precluded. Now I have found in the operation of my device, that the disassociation products of the halides, particularly chlorine, present in the liquid by way of impurity, tend to disrupt the after has the characteristic of large capacity per film of o ide a d c se Current e unit area, I am able to connect three or four ver, by ad 130 t ec y a trace of units in series, each of which charges on 1.5 mercury, the acetate of either lead or silver that 3 volts and still obtain suflicient capacity in aggreyield an insoluble halide, the injurious eifects of gate for practical purposes. Thus the multiforeign matter, are removed. While heretofore, condenser unit described hereinafter functions I have referred to the liquid as an electrolyte, it admirably as a low impedance shunt for current is to be distinctly understood that after the film ripples ordinarily present in the output circuit has been formed by the application of potential, 35

of a rectifier supplying a thermionic tube filament circuit of standard potential. While its operation as a current filter is marked, the condenser has a broad field of utility throughout circuits in general which require a condenser of relatively small dimension but capable of absorbing a large charge and sealed to the atmosphere. /Vith the aforesaid and other objects in view, my invention will be more fully described in relation to the specific embodiments illustrated in the d wing, in which:

is elevational view of the condenser rtion broken away;

transverse section taken along line my device appears to be substantially devoid of electrolytic action, the acetate performing apparently no function otherthan that of a mere conductor and accordingly, the container can be sealed and made rugged. In a sense, the condenser may be considered as comprising a metal sheet as one plate and the body of liquid as the other separated by an oxide dielectric. In practice however, the two metal plates are located quite close together and both probably constitute active electrodes.

The condenser is made by rolling the aforesaid sheets on a mandrel, the plate members being separated by the layer of absorbent, the unit taking on a spiral form as shown in Fig. 2 and plan showing a plurality of consubsequently enclosed within paper carton made according to my invention soaked in paraffin to waterproof. together; and Central core left by the mandrel, is packed es to a multi-condenser unit in flat with asbestos or other porous material preferably in fialse form, leaving space i between the upper surface of the core and sealing wax cover I for gas to collect during the film forming period. Before the seal is applied however, electrolyte is admitted to the container in quantity just suflicient to saturate the absorbing material. At 9, I-show two clip terminals to which connection is made from the metallic plates.

The words formed or forming used throughout the specification and claims refer to the process of producing a current-blocking film on an electrode surface by the passage of current through the device, ordinarily sumcient to produce the liberation of gas as described above.

Fig. 3 illustrates an arrangement for securing together by wrapper ID, a plurality of condensers as a unit. As will be noted the connection in series is such that each condenser is subjected to only a fraction of the applied potential, the fractional amount being sufllcient to completely charge the condenser but insuflicient to cause appreciable electrolysis except during the fllm forming period. The spaces II are packed with a suitable filling material.

While I have described my condenser as being of cylindrical form, it is obvious that a fiat unit comes within the purview of the disclosure. Thus in Fig. 4, I show a condenser stack readily constructed of four complete units having flat form and effectively connected in series as in Fig. 3 by placing the metallic plate of one condenser contiguous with that of the unit adjacent thereto. A single element may replace the double plate if the stack is-rnanufactured as a whole. As in Fig. 1, porous material impregnated with potassium acetate is interposed between the conducting surfaces and if desired, the stack may be placed in a sealed container to facilitate handling.

I claim:

1. A condenser comprising two metallic film forming plates separated by an absorbent containing an electrolyte having a relatively large proportion of potassium acetate.

2. A condenser comprising two film-forming electrodes immersed in a solution containing a relatively large proportion of potassium acetate, and a soluble salt of a metal whose halide is insoluble.

3. A condenser comprising a sealed receptacle enclosing two film forming electrodes separated by a solution of potassium and lead acetates.

4. A condenser comprising two film-forming electrodes immersed in a solution containing a relatively large proportion of potassium acetate, and a halide precipitant.

5. An electrolytic condenser comprising a plurality of plates of an alloy containing a substantial amount of silicon with an electrolyte containing a relatively large proportion of potassium acetate.

6. An electrolytic condenser comprising a plurality of plates of a nickel-silicon alloy with an electrolyte containing a relatively large proportion of potassium acetate.

7. An electrolytic condenser comprising a pinrality of sheets of nickel silicon alloy with intervening layers of absorbent material containing a solution having a relatively large proportion of potassium acetate.

8. The condenser of claim 7 with the soluble salt of a metal whose halide is insoluble added to the solution.

9. A condenser comprising two film-forming electrodes immersed in a solution containing a relatively large proportion of potassium acetate.

10. A condenser comprising two film-forming electrodes separated by a solution of potassium and lead acetate.

VANNEVAR BUSH. 

